The present invention relates in general to control of fluid-dynamic induced lift on foils fixed to the hull of a sea going vessel during propulsion thereof.
An important factor in the maneuvering of crafts or vessels within a fluid medium such as seawater involves control over the fluid dynamic lift induced thereon during propulsion. Thus, safe handling of a high-speed ocean going vessel can be enhanced by providing instantaneous control of lift forces produced by a control surface. Ride control on high speed ocean vessels require rapid changes in control surface lift forces to compensate for changing sea state conditions which may instantly alter pitch or roll conditions of the vessel. Currently, changes in the angle of attack of a control surface are required to change the lift imposed thereon. Because of the large hydrodynamic forces experienced by the control surface, changes in the angle of attack and thus lift, often require large hydraulic motor capabilities and can only produce slow changes in lift. These slow changes in control surface lift are inadequate for superior ride control on a high-speed ocean going vessel and furthermore require large actuation forces. It is therefore an important object of the present invention to provide for simple, rapid and low power modification of control surface lift so as to increase the ride control available for high speed vessels.
In accordance with the present invention, selectively controlled flow separation means is provided for projection simultaneously from both the upper and lower surfaces on the fixed stabilizer of a flapped airfoil, so as to modify the lift produced by the flapped airfoil at all flap angles. Such lift modification by the separation means significantly involves rapid directional reversal of the lift for all angular positions of the flaps within its operational range of position angles.